The invention relates to a method for generating an electrical signal by means of a sensor device as a function of a change from an active phase to a passive phase in a space filled with a fluid, wherein a sensor element of the sensor device detects the heat transfer between the sensor element and the fluid over time. The invention further relates to a sensor device for executing the method, and to the use of such a sensor device.
Automatically operating flushing devices are preferably used for flushing urinal bowls in public restrooms. These are understood to be flushing devices which either perform flushing at defined time intervals, regardless of whether the bowls had been used or not, or flushing devices, wherein flushing is started based on any arbitrary, for example mechanical or electrical, signal, for example, which is generated when the bowls are used.
The disadvantage of the flushing devices operating at time intervals lies in that, when the bowls are intensely used, they are flushed too seldom, which leads to a lack of sanitation and the emission of odors while, in case of little use, flushing operations take place without the bowls having been used, which means a waste of water. Furthermore, periodically occurring flushing operations also take place while the bowls are being used, which can be unpleasant for the user of toilet bowls in particular. Flushing devices, which are started by signals generated by sensors when the bowls are used, do avoid the disadvantage of too few, too many or chronologically undesired flushing operations. Systems with photoelectric barriers are most frequently employed, wherein a beam impinging on a optical sensor is reflected by the user, wherein the flushing device is activated immediately or after the user has stepped back out of the range of the beam. The disadvantage of such and other sensor-controlled flushing devices lies mainly in that the easily visible sensor devices often do not operate well or not at all, because they are purposely or inadvertently disrupted or destroyed, and that flushing is also triggered by persons present in the range of the beam, even if the bowl has not been used at all.
In addition to this, there is the danger of water damage, both with periodically operating and controllable flushing devices, because of overflowing bowls, because the flushing operations continue to be performed even if the drains are plugged.
It is therefore the object of the invention to prevent the mentioned disadvantages and to propose a method with which electrical signals for activating the flushing are generated, wherein the danger of water damage because of overflowing or plugged up drains is avoided.
It is a further object of the invention to create a sensor device operating in accordance with the novel method, whose production and installation is simple and cost-effective and which operates with few malfunctions, or respectively almost maintenance-free.
A still further object of the invention is to propose the use of such a device.
The principle of the invention resides in generating an electrical signal as a function of a voltage change. The changing voltage can be picked up at a sensor element to which a voltage has been applied. Essentially, the sensor elements consist of a material with a temperature-dependent electrical conductivity, which is located in a space filled with a fluid. In a passive phase, i.e. when no electrical signal is to be generated and therefore the voltage is to remain constant, this sensor element is continuously heated or cooled, so that it is brought to a passive temperature, which in any case lies outside the temperature range of the fluid in the following active phase, and generally also outside of the temperature range of the fluid in the passive phase. This has the result that in the passive phase a heat transfer either from the sensor element to the fluid or from the fluid to the sensor element takes place, which becomes stationary after a certain time. If now a change occurs in the vicinity of the sensor element in the space filled with fluid, which increases the heat transfer, the temperature of the element changes because of the greater or smaller amounts of heat being absorbed or given off per unit of time, since it is heated or cooled not to a constant temperature, but with a constant output. Within the framework of the present invention, such a change in the fluid-filled space is to be understood not only to be a change in the temperature of the fluid, but also a change of the chemical consistency, and therefore of the heat-absorption capability of the fluid. In other words, a replacement of the fluid present in the state of rest by another fluid, and/or a change of the aggregate state of the fluid, and/or a change in the flow rate of the fluid, and/or a change in the level of a liquid fluid. It is known that the amount of heat absorbed over time by the fluid is not only a function of the temperature difference between the element and the fluid, but also of the capacity of the fluid for absorbing heat, essentially therefore of the flow rate of the fluid, wherein a rapid flow increases the heat transfer because of convection occurring in the course of this. The active phase starts with the change, i.e. that, as already mentioned, the heat transfer between the sensor element and the fluid is changed because of the change in the fluid-filled space, which results in a change in the temperature of the sensor element and therefore a change in the output voltage. The latter is used directly or indirectly as a signal, for the generation of which the novel method, or respectively the novel sensor device, is used.
A preferred use of the novel sensor device is the automated flushing of urinal or toilet bowls. Here, water damage because of overflowing is prevented, even when the outlet is plugged up. If the outlet of the urinal or toilet bowl is plugged up, it is automatically provided that no change in the amount of heat given off by the element, and therefore no heating or cooling of the element, no change of the output voltage and no further flushing operation takes place at all. Moreover, flushing is only triggered if the urinal or toilet bowl is actually used.
Installing the novel sensor device, for example in existing urinal bowls, is simple. The sensor device, or possibly elements thereof, can be easily replaced in case of outages.
The sensor device, or respectively the sensor element, can be cast into a wall simultaneously with the construction of the latter. However, in this case it can generally not be exchanged, so that this concept can only be used for sensor elements with a very long service life and very slight tendencies to become defective. The problems regarding the service life, or respectively the tendency to become defective, become moot if, in place of the sensor device itself, only a holding arrangement for the latter is integrally provided in the wall, in which an exchangeable sensor device can be fastened.
The sensor device, or respectively the sensor element can be installed in various locations. Fastening locations can be provided ahead of or behind the odor barrier on a lower, or a lateral or, suspended from an upper, fastening surface, wherein the latter has the advantage that the danger of a covering of dirt over the sensing area is less. In any case, it is advantageous if the sensing area of the sensor device is not arranged in a depression of the wall, but flush with the wall or projecting slightly into the interior, so that it is actually washed by the flushing water. In this way the formation of a sump of urine deposits and/or other soiling is prevented in an efficient manner.
It is particularly advantageous to mount the sensor device, or respectively the sensor element, at a location which is not accessible to the users. In this way the purposeful or possibly also inadvertent damage is prevented. In public restrooms in particular it is prevented vented in this way that the sensor device, or respectively the sensor element, and therefore the flushing device, become the victims of acts of vandalism.
Up to now, the use of the novel device has been mainly addressed in connection with urinal bowls. Such a sensor device can of course also be employed in other ways, in the sanitary field not only with toilet bowls, but also in sinks of the most diverse different kinds. Outside of the sanitary field, the sensor device can also be used in the most diverse ways, for example as a leak detector for liquid media, for example oil catch basins, as a low filling level detector, in particular in the field of aquarium keeping, as a protection of pumps against dry running, as an alternative to floats for measuring the level of liquids, as well as a replacement for mercury switches. It should be pointed out that the sensor device is also suitable in cases in which flammable or explosive fluids are involved.
In connection with toilet bowls it is necessary to prevent a seated or crouching user from being splashed in an undesirable manner when flushing is actuated. To this end flushing can be delayed, for example. Another option lies in actuating flushing immediately, wherein the toilet bowl must be shaped in such a way that the user is not splashed, by means of which odor emissions are minimized. Finally, the invention can also be used in combination with an automatic device, such as the one known by the name xe2x80x9cKlosomatxe2x80x9d, for example.
The device advantageously has a regulator, by means of which the chronological flushing behavior can be affected, possibly in an adjustable manner. For example, in connection with urinal bowls it is advantageous to provide wetting of the wall, on which the stream of urine impinges, by means of pre-flushing immediately when they are used, in this way the reflection and spraying of the stream can be prevented and the problem-free run-off along the wall wetted by the pre-flushing can be assured. To prevent too long a time without flushing, it is also advantageous to trigger flushing at defined periods of time, even if the bowl had never been used since the previous flushing. Such flushing can also take place with an increased amount of water, if necessary, and can be used as periodic cleaning flush, so to speak, or can assure the suppression of odors. It is also possible to add a cleaner, or respectively disinfectant or a deodorizing agent to the flushing water for a cleaning flush for increasing the sanitary standards, or respectively for preventing offensive odors.
Preferably the signal has a strength which does not require further, or at least no significant amplification.
The reaction of the sensor element to changed conditions of its environment, which result in a change in the terminal voltage, takes place all the faster, the faster the required temperature change of the NTC, or respectively PCT resistor takes place. To achieve this it is advantageous if the mass is low and the temperature difference between the temperature at rest and the initiating temperature is great. A small mass is also advantageous because it reduces the energy used for heating, or respectively cooling it. But a large temperature difference has the result in principle that the energy requirement for heating or cooling is comparatively great. However, this is not very important because of the heating or cooling energy required which, absolutely considered, is small.
The sensor device itself is simple to manufacture and cost-effective. It can be produced in such a way that it is not attacked by either urine or chemicals, such as strong cleaning agents, for example. As already mentioned, it is also suitable for contact with explosive and flammable materials, since no spark, which touches the fluid(s), is generated by the electrical signal.
Heating or cooling of the sensor element, whose electrical resistance is a function of the temperature, can be provided directly or indirectly. With indirect heating, or respectively cooling, a heating, or respectively cooling element is heated, or respectively cooled, which in turn heats the element by heat conduction, convection and/or radiation. The heat transfer between the heating resistor and the sensor element is preferably aided by a material with good heat conduction, which connects the two. This material can also fill the entire free space inside the housing. With direct heating, or respectively cooling, the sensor element itself is electrically heated, or respectively cooled, which has the advantage that only two cables are needed for wiring in place of three or four cables with indirect heating, or respectively cooling, but with the disadvantage of the non-independent voltage.
In general, the sensor element and, if desired, the separate heating, or respectively cooling element, as well as the wiring, are arranged in a sensor housing made of a material which is insensitive to the fluids with which it comes into contact, and which is hermetically sealed. Suitable materials are glass, plastics, such as teflon, for example, and metals which are resistant to the respective fluids.
It is further possible to design the sensor element and the housing integrally, wherein the element is embodied housing-like, so to speak, and only needs to receive the wiring and, if required, i.e. with indirect heating, or respectively cooling, also the heating, or respectively cooling element.
Further details and advantages of the invention will be explained in what follows by means of exemplary embodiments of the invention, making reference to the drawings.